The Hamilton Conservation Authority is launching a five-year study of local hardwood forests to see how their health is being affected by stresses like invasive plants and pests, tree diseases, deer overpopulation, human activity and climate change.

Terrestrial ecologist Lesley McDonell said the study will monitor two different plots per year at the Valens, Dundas Valley, Iroquoia Heights and Felker’s Falls conservation areas, as well as at scattered locations elsewhere in the watershed.

Each of a total of 50 plots will measure 20 by 20 metres and be located about 150 metres inside the forest’s edge.

The goal is to get a statistically relevant sample for the study areas that can be used to track the health of trees, forest vegetation, birds and indicator species like red-back salamanders, she said.

“Right now we don’t have a lot of terrestrial monitoring going on in the watershed,” said McDonell, who joined the authority in her newly created position in April.

“We’ll be able to see what’s the state of the system right now and as we go through time take a look and see how it’s changing, whether positively or negatively.”

McDonell said each plot will have five smaller subplots to measure sapling regeneration, the diversity of shrub types and invasive species like garlic mustard and the emerald ash borer.

Forty wooden boards will also be placed on the ground in each conservation area to monitor red-back salamanders, chosen because they are common, live in the same spot during a lifespan of 10 or more years and breathe through their skin, she said.

The boards, about a square foot each, will be turned over four times each spring to see how populations living underneath them have changed.

“They’re a great indicator of ecological change,” McDonnell said in a presentation on the study to the authority’s conservation areas advisory board.

“If something happens in the environment and there’s a change, the change in the population is fairly fast, whereas in trees it takes you a really long time to see that change.”

The forest plots will also monitor tree mortality and other signs of tree health, the proportion of birds that nest in the canopy, shrubs or on the ground, and soils – the latter also seen as a key component.

“We can look at everything that’s above the ground, but if we don’t ever look down, we don’t know what’s there and what’s maybe affecting the system, and we can’t see chemicals, bioaccumulation of metals, anything like that,” she said.

McDonell said she hopes to set up some of the initial 10 plots in the coming month and eventually conduct similar studies on local wetlands and meadows.

In the meantime, a broader monitoring program will work on identifying the locations of at-risk species like butternut trees to help keep human activity away as well as track invasive species and potential ways to remove them, she said.